Tap and Go allows users to quickly migrate to a new Android device, using NFC and Bluetooth to transfer Google Account details, configuration settings, user data and installed applications

A flashlight-style application is included, working on supported devices with a camera flash.

User-customizable priorities for application notifications.

Smart lock feature

SELinux in enforcing mode for all domains

Updated emoji

Improved accessibility support (e.g. switch access support)

Block-based over-the-air (OTA) updates for new devices

5.0.1 - December 2, 2014

A few bugfixes, including resolving issues with video playback and password failures handling

5.0.2 - December 19, 2014

Fixes a bug with TRIM support, which prevented devices from the nightly on-charger cleanups of file system allocations if the device was turned off while being charged, or if it was charged during the day

Changes how alarms wake the CPU, and how alarms compete for system resources

Android 4.4 KitKat with wearable extensions (API level 20)

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4.4W - June 25, 2014

Initial release of Android Wear platform for smartwatches: the same as Android 4.4 "KitKat", but with wearable extensions added

4.4W.1 - September 6, 2014

UI updates for Google Maps navigation and alarms

4.4W.2 - October 21, 2014

Offline music playback

GPS support

Android 4.4 KitKat (API level 19)

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4.4 - October 31, 2013

Refreshed interface with white elements instead of blue

Clock no longer shows bold hours; all digits are thin. The H, M, and S markings for the stopwatch and timer have been removed, leaving just the numbers.

Ability for applications to trigger translucency in the navigation and status bars

Ability for applications to use "immersive mode" to keep the navigation and status bars hidden while maintaining user interaction

Action overflow menu buttons are always visible, even on devices with a "Menu" key, which was officially deprecated by Android 4.0.

Restriction for applications when accessing external storage, except for their own directories

Optimizations for performance on devices with lower specifications, including zRAM support and "low RAM" device API

Wireless printing capability

NFC host card emulation, enabling a device to replace smart cards

WebViews now based on Chromium engine (feature parity with Chrome for Android 30)

Expanded functionality for notification listener services

Public API for developing and managing text messaging clients

Storage Access Framework, an API allowing apps to retrieve files in a consistent manner. As part of the framework, a new system file picker allows users to access files from various sources (including those exposed by apps, such as online storage services).

New framework for UI transitions

Sensor batching, step detector and counter APIs

Settings application now makes it possible to select default text messaging and home (launcher) application

Audio tunneling, audio monitoring and loudness enhancer

Built-in screen recording feature (primarily for developers, as usage of ADB is required)

Native right-to-left, always-on VPN and application verification.[106] A new NFC stack was added at the same time.

Accessibility improvements: triple-tap to magnify the entire screen, pan and zoom with two fingers. Speech output and Gesture Mode navigation for blind users

New clock application with built-in world clock, stop watch and timer

All devices now use the same interface layout, previously adapted from phones on 4.1 for smaller tablets (with centered software buttons, the system bar at the top of the screen, and a home screen with a dock and centered application menu), regardless of screen size

Increased number of extended notifications and Actionable Notifications for more applications, allowing users to respond to certain notifications within the notification bar and without launching the application directly

SELinux

Premium SMS confirmation

Group Messaging

4.2.1 - November 27, 2012

Fixed a bug in the People application where December was not displayed on the date selector when adding an event to a contact

New two-pane Email UI to make viewing and organizing messages more efficient, allowing users to select one or more messages

Hardware acceleration

Support for multi-core processors

Ability to encrypt all user data

HTTPS stack improved with Server Name Indication (SNI)

Filesystem in Userspace (FUSE; kernel module)

Applications write access to secondary storage (memory cards on devices with internal primary storage) is disabled outside of designated, app-specific directories, while full access to internal primary storage is still allowed through a separate application-level permission.

Android 2.3.3–2.3.7 Gingerbread (API level 10)

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2.3.3 - February 9, 2011

Several improvements and API fixes

2.3.4 - April 28, 2011

Support for voice or video chat using Google Talk

Open Accessory Library support. Open Accessory was introduced in 3.1 (Honeycomb) but the Open Accessory Library grants 2.3.4 added support when connecting to a USB peripheral with compatible software and a compatible application on the device

Switched the default encryption for SSL from AES256-SHA to RC4-MD5.

2.3.5 - July 25, 2011

Improved network performance for the Nexus S 4G, among other fixes and improvements

Fixed Bluetooth bug on Samsung Galaxy S

Improved Gmail application

Shadow animations for list scrolling

Camera software enhancements

Improved battery efficiency

2.3.6 - September 2, 2011

Fixed a voice search bug

(The 2.3.6 update had the side-effect of impairing the Wi-Fi hotspot functionality of many Canadian Nexus S phones. Google acknowledged this problem and fixed it in late September.)

2.3.7 - September 21, 2011

Google Wallet support for the Nexus S 4G

Android 2.3–2.3.2 Gingerbread (API level 9)

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2.3 - December 6, 2010

Updated user interface design with increased simplicity and speed

Support for extra-large screen sizes and resolutions (WXGA and higher)